The present invention relates to a method of making tubular, curved or straight molds for continuous casting, under utilization of a copper alloy.
German printed patent application No. 25 33 528 discloses a method of making such a mold by deforming a copper or copper alloy blank by means of explosives for forming the blank in order to obtain the desired contour of the mold. This method offers the advantage of a high-quality surface of the resulting mold; also, the dimensions of the cavity attained in this fashion are very accurate. Additionally, the surface of the mold is actually hardened. Assuming, for instance, an original hardness of 40 Rockwell B, the explosive-forming method above will result in a hardness of from 50 to 75 Rockwell B.
The explosion deforming or forming as described is disadvantaged by the fact that the resulting wall thickness is too low to permit any significant subsequent reduction, e.g., by means of cold-working. Consequently, the overall strength of the mold and, therefore, the stability as to shape and integrity of the cross section is fairly poor. Moreover, cold-working is usually employed in order to strengthen the material; but as soon as the temperature rises to 350.degree. C., that process reverses itself so that a highly used mold wears out rather quickly. The mold's strength can be increased to some extent through appropriate selection of the copper alloy constituents. Unfortunately, the heat conduction goes down; and such a mold may have the tendency of cracking in the surface level of the molten material.